I am going back to a single exhaust and want to put both the wide band and the stock narrow band in just after the Y collector so they read both banks. To do this the sensors would be roughly 4 feet back from the header collectors. Both are heated so other then a possible delayed reading I can't see that it would be a problem but I thought I had better ask.

 

well on a wideband and sure its the same on the narrow its just not as accurate.. your supposed to put them closer like if you had longtubes your supposed to put them in the collector.. my aem wideband im getting says to mount it at least 18" downstream from the exhaust port. so closest with my longtubes would be the collector if you have manifolds you can do it closer but to read both banks it requries to seperate sensors to be correct otherwise puting them that far back your just wasting your time and money... hope that helps.. check out aem or whoever and read the install pdf file and it will most likely answer your questions as well